Using annual chest CTs to screen for lung cancer, the leading cause of cancer death in the United States, can reduce mortality by up to 20%; however, fewer than 4% of eligible Americans are screened. The US Preventive Services Task Force endorses lung cancer screening (LCS) for high risk current and former smokers. At the same time, LCS poses significant risks, such as false positives and invasive procedures. Accordingly, guidelines recommend and Medicare requires that patients engage in a shared decision making visit prior to screening. Unfortunately, primary care providers rarely discuss, and consequently patients rarely receive, LCS. Patient, provider, and system barriers contribute to low LCS rates. Many patients are unaware that LCS exists, that it is effective, or that they qualify for screening. The risks and benefits of LCS vary substantially according to patients? risk factors making general education about LCS difficult. Healthcare providers have poor understanding of the screening criteria and lack the time and personalized information needed for shared decision making discussions. Decision aids for LCS are a partial solution; they can increase patient awareness, deliver personalized information, and help patients make a screening decision. However, they fail to address many provider and system barriers. Our team has developed an innovative digital outreach strategy called mPATH-Lung (mobile Patient Technology for Health ? Lung) based on Social Ecological Theory and the Integrative Model of Behavior. mPATH-Lung has multilevel functionality: it (a) queries the electronic health record to identify potential screening candidates, (b) sends those individuals electronic invitations to visit a web-based LCS decision aid that helps them make a screening decision concordant with their values, and (c) empowers patients to electronically request an LCS clinic appointment for the mandated shared decision making and subsequent screening. Electronic program summaries are sent to patients and providers, ensuring shared decision making visits occur with informed participants. This project will determine the impact of mPATH-Lung on patient decision making and receipt of LCS in a pragmatic randomized controlled trial using a mixed methods design. The Specific Aims of the proposal are to: 1) Determine the effect of mPATH-Lung on receipt of LCS in a pragmatic randomized-controlled trial of 1318 primary care patients in two large health networks with a catchment area extending to 5 states; 2) Elucidate the drivers of patients? LCS decisions and screening behavior using a values clarification exercise and semi-structured interviews with at least 60 patients selected to represent the spectrum of decision-behavior concordance; and 3) Explore implementation outcomes that will impact the sustainability and dissemination of mPATH-Lung using program data, surveys, and interviews. This project could decrease lung cancer morbidity and mortality by broadening the use of LCS while simultaneously supporting patient-centered care. Importantly, our digital outreach design could have broad applicability to other health conditions, expanding the impact of this proposal beyond LCS.